What is it?

Swimmer’s Itch is the common name given to Cercarial Dermatitis. It is a rash caused by a microscopic parasite called Cercariae.

How do I get it?

You get Swimmer’s Itch by swimming in water infested with cercariae. The cercariae burrow into human skin causing an allergic reaction or blisters.

How is water infected?

Cercariae infect birds and some mammals like racoons and muskrats, living in the blood of the host animal. They lay eggs in the blood which passes through the host and is excreted along with the feces of the infected animal. If the eggs come into contact with water, the eggs hatch and release free swimming, ciliated miracidium, also known as the larvae. The larvae then infect aquatic snails or other gastropods that are found in water to develop. The larvae multiply and grow into another microscopic organism called cercariae (hence the name cercarial dermatitis). Once mature, the cercariae are released from the aquatic snail and swim around to infect another host animal, such as birds, to continue the cycle. If the cercariae attach themselves to humans, they cause blisters, rashes or an allergic reaction. Because the larvae cannot develop inside humans, they die while burrowing into the skin.

What does Swimmer’s Itch look like?

Symptoms of Swimmer’s Itch develop minutes to days after swimming in contaminated water. Small reddish pimples usually appear within 12 hours. Your skin may:

  • Tingle, burn or experience persistent itching.
  • Develop small reddish pimples.
  • Develop small blisters.

Symptoms typically disappear between 1-3 weeks.

How do I treat Swimmer’s Itch?

Most cases of Swimmer’s Itch do not require professional medical attention. The following may help for relief:

  • Corticosteroid creams applied gently to the affected area.
  • Cool cloths or compressants applied delicately.
  • Epsom salt baths, or bathing in baking soda.
  • Soaking the affected area in an oatmeal bath.
  • Anti-Itch lotions.

Scratching may cause the rash/blisters to become infected. If symptoms are severe, your health care provider may suggest stronger, prescription strength lotions or creams to alleviate symptoms.

Who is at risk of Swimmer’s Itch?

Everyone. Even if you have had it before, you are still at risk of getting it again.

Can it be spread?

No. Swimmer’s Itch is not a contagious condition.

How do I prevent myself from getting it?

You can prevent Swimmer’s Itch by:

  • Not swimming in areas known to have cercariae or Swimmer’s Itch problems.
  • Do not swim or wade in marshy areas where snails are commonly seen.
  • Towel dry or shower immediately after swimming.
  • Do not attract birds to areas where people swim.
  • Knowing how it is caused and recognizing the signs of potential swimmer’s itch hazards.

Will infected water always be unsafe?

No. Many factors contribute to Swimmer’s Itch that changes constantly. There is no way to know how long water will be unsafe for. Larvae survive for ~24 hours after being released, but will always be released from an infected snail. Minimizing the causing factors (removing snails and birds from the swimming area) is the best way to keep water safe from cercariae.